Fiber optic communications networks may increase the amount of information carried on an optical fiber by multiplexing different optical signals on different wavelengths using wavelength division multiplexing (WDM). In a WDM passive optical network (PON), for example, a trunk fiber carries optical signals at multiple channel wavelengths to and from an optical branching point and the branching point provides a simple routing function by directing signals of different wavelengths to and from individual subscribers. In this case, each subscriber may be assigned one or more of the channel wavelengths on which to send and/or receive data.
To transmit and receive optical signals over multiple channel wavelengths, an optical line terminal (OLT) in a WDM-PON may include a multi-channel transmitter optical subassembly (TOSA), a multi-channel receiver optical subassembly (ROSA), and associated circuitry. One challenge with such OLT transceiver modules is providing temperature control in a relatively small space and with relatively low power consumption.